Re: [PATCH v3 6/7] iommu/dma: Centralise iommu_setup_dma_ops()

From: Baolu Lu
Date: Sat Feb 10 2024 - 06:28:06 EST

On 2024/2/10 0:50, Robin Murphy wrote:
It's somewhat hard to see, but arm64's arch_setup_dma_ops() should only
ever call iommu_setup_dma_ops() after a successful iommu_probe_device(),
which means there should be no harm in achieving the same order of
operations by running it off the back of iommu_probe_device() itself.
This then puts it in line with the x86 and s390 .probe_finalize bodges,
letting us pull it all into the main flow properly. As a bonus this lets
us fold in and de-scope the PCI workaround setup as well.

At this point we can also then pull the call up inside the group mutex,
and avoid having to think about whether iommu_group_store_type() could
theoretically race and free the domain if iommu_setup_dma_ops() ran just
*before* iommu_device_use_default_domain() claims it... Furthermore we
replace one .probe_finalize call completely, since the only remaining
implementations are now one which only needs to run once for the initial
boot-time probe, and two which themselves render that path unreachable.

This leaves us a big step closer to realistically being able to unpick
the variety of different things that iommu_setup_dma_ops() has been
muddling together, and further streamline iommu-dma into core API flows
in future.

Signed-off-by: Robin Murphy<robin.murphy@xxxxxxx>
v2: Shuffle around to make sure the iommu_group_do_probe_finalize() case
is covered as well, with bonus side-effects as above.
v3:*Really* do that, remembering the other two probe_finalize sites too.
arch/arm64/mm/dma-mapping.c | 2 --
drivers/iommu/amd/iommu.c | 8 --------
drivers/iommu/dma-iommu.c | 18 ++++++------------
drivers/iommu/dma-iommu.h | 14 ++++++--------
drivers/iommu/intel/iommu.c | 7 -------
drivers/iommu/iommu.c | 20 +++++++-------------
drivers/iommu/s390-iommu.c | 6 ------
drivers/iommu/virtio-iommu.c | 10 ----------
include/linux/iommu.h | 7 -------
9 files changed, 19 insertions(+), 73 deletions(-)

For changes in Intel IOMMU driver,

Reviewed-by: Lu Baolu <>

Best regards,